It is generally known to use stents (=vascular prostheses), placed using fluoroscopy, in angiography. For this purpose, the stents have to be very conspicuous so that they are precisely deployed at the desired location. However, stents are often not very conspicuous because it is necessary to use the lowest x-ray doses possible, especially in more time-consuming procedures. The same situation arises when using guide wires which have to be very thin and, as a consequence, they too are often not visible enough when irradiated. Similar problems also occur when using catheters, or when using implants in general.
Previously the x-ray spectrum in examinations and treatments controlled by fluoroscopy was optimized to the effect that the stents and guide wires, composed of different metal alloys, had the largest possible contrast with respect to the surrounding tissue. However, the contrast, and hence the visibility, often remained unsatisfactory, especially in the case of low x-ray doses.
In order to nevertheless ensure the visibility of stents, markers composed of a heavy metal, for example gold, are affixed to the ends of the stents. These are more visible in conditions prevailing in fluoroscopy. However, only individual points are highlighted. The visibility of the precise progression of stents, catheters or guide wires over their entire length is not improved. Furthermore, markers do not allow monitoring of the correct deployment of a stent.